The 12db of gain is software gain, and presonus has documents on it's site specifically saying the SM57/58 doesn't have enough output to get a good signal with the firebox. We're talking preamps cranked, 12db checked, and it's barely tickling the meters in Logic or Record.

FIREBOXID #1133Why can't I get enough gain from my FireBox pre's with my SM58?In order to keep the FireBox in compliance with IEEE 1394 powering standards, the voltage rails were reduced, which resulted in a slightly lower preamp gain than the preamps found in other PreSonus preamps. The FireBox has approximately 45 dB of analogue gain with an additional 12 dB via the boost for a total of 57 dB total gain. This is sufficient for the majority of the FireBox's users' needs. However, in situations where a low output microphone is used, quiet sound source is recorded, or very hot digital signal is required, it is recommended to pick up an external preamp (like the BlueTube DP, Tube Pre, Eureka, ADL 600, etc) and use it through line inputs 3 & 4.

Take for example the Shure SM58. Based on its specifications, a 94 dB signal into the microphone will result in an output signal of -54 dB. (90 dB is roughly equivalent to the volume of a blender.) So if you record something as loud as a blender with an SM58, the result would be a maximum attainable signal level of +3 dBV (or -15 dBFS). An SM57 has an even lower output (-56dBV/Pa) and would result in a maximum signal level of approximately +1dBV. Conversely, the Shure KSM27 condenser microphone has a sensitivity of -37 dB/Pa. This gives a preamplified signal of +20 dBV (or +3 dBFS) -- a signal roughly 30 times louder than that of the SM58.Tags: -"

So, I am going to get a condenser and try that before buying another preamp.

There isn't much in the way of alternatives in that price range. The A/D converter sounds great- this no latency monitoring works perfectly, and my other gear sounds great through it. I'll try the condenser and let you know how it comes together.

I've tried the maudio gear that is priced similar and it sounded poor.

OK, trials and tribulations continue- decided to stay with the SM58 as I would have needed two condensers to do what I wanted, and I wanted ot mic cabs occasionally.

Went to GC and bought a TubePre, still dont get -CENSORED- for signal off the SM58. Beginning to think it's the SM58. Furthermore, I wanted to swap the crappy tube with one of my decent tubes, and a couple of the screws were stripped out on the TubePre, right out of the factory. The only plus is I got GC to pricematch some online company, so I bagged the TubePre for $99.

I'm dragging everything down to GC with my MacBook Pro tomorrow to sort this out. Definitely going to exchange the TubePre, test the new one with a different SM58 and the FireBox, see where I get.

What started out as a $300 way to lay down sketches at home is starting to grow out of control.

What I do have and use for dynamic headphones: Sennheiser MD-421, Electrovoice SRO-RE11 and a TEAC MC-105 (probably from the late 60's early 70's)

Sensitivity of the SM 58 is better than the RE11 and TEAC MC-105 according to specs posted on-line (I don't have a manual or spec sheet for the SRO-RE11 - it's pretty ancient)

I haven't had issue with vocals for either the EV or the TEAC microphone, or the MD421 for that matter.

I use a condenser with my Larrivee just because I like the sound so much better than a dynamic mic on it. I've never bothered with the dynamic mics and the Larrivee because with my CAD M-177 condenser, I just like the sound.

What source material are you trying to use? Also, have you tried using the wall-wart power supply with the FireBox - that may help to provide enough rail voltage for the pre-amp circuit.

I have had issues with the Firebox with some bleed-over from the output circuitry to inputs (with no outputs plugged in - no headphones, no monitor speakers, nothing).